The present invention relates to an instrument for urging an orthopedic rod into a recess in an orthopedic device and more particularly, to an instrument for securing a spinal rod to a coupling element.
The spinal column is a highly complex system of bones and connective tissues that provides support for the body and protects the delicate spinal cord and nerves. The spinal column includes a series of vertebral bodies stacked one atop the other, each vertebral body including an inner or central portion of relatively weak cancellous bone and an outer portion of relatively strong cortical bone. Situated between each vertebral body is an intervertebral disc that cushions and dampens compressive forces exerted upon the spinal column. A vertebral canal containing the spinal cord and nerves is located behind the vertebral bodies.
There are many types of spinal column disorders, including scoliosis (abnormal lateral curvature of the spine), kyphosis (abnormal forward curvature of the spine, usually in the thoracic spine), excess lordosis (abnormal backward curvature of the spine, usually in the lumbar spine), spondylolisthesis (forward displacement of one vertebra over another, usually in a lumbar or cervical spine) and other disorders caused by abnormalities, disease or trauma, such as ruptured or slipped discs, degenerative disc disease, fractured vertebra, and the like. Patients that suffer from such conditions usually experience extreme and debilitating pain, as well as diminished nerve function.
Surgical techniques commonly referred to as spinal fixation use surgical implants and/or mechanical immobilization to fuse two or more vertebral bodies of the spinal column. Spinal fixation may also be used to alter the alignment of adjacent vertebral bodies relative to one another so as to change the overall alignment of the spinal column. Such techniques have been used effectively to treat the above-described conditions and, in many cases, to relieve pain.
One spinal fixation technique involves immobilizing the spine using orthopedic stabilizing rods, commonly referred to as spine rods, which are positioned generally parallel to the spine. This may be accomplished by exposing the spine posteriorly and fastening bone screws to the pedicles of vertebral bodies. The pedicle screws are generally placed two per vertebra and serve as anchor points for the spine rods. Coupling elements or implants adapted for receiving a spine rod therethrough are then used to join the spine rods to the pedicle screws. A set screw or fastener then fastens the spine rod into a seat in a coupling element.
Instruments are utilized for inserting a spine rod into position within an orthopedic device such as a coupling element. Surgeons have encountered considerable difficulty when attempting to use these instruments to insert a spine rod into the seat of the coupling element and then inserting a fastener to secure the set up. For example, U.S. Pat. No. 5,910,141 to Morrison provides a rod introduction apparatus capable of laterally aligning a rod with an implant and vertically advancing the rod into position in the implant. The instrument, however, is difficult to use since it requires two hands, one hand to hold the instrument while it clamps the implant and one hand to operate the lateral alignment and vertical alignment means to properly position the rod in the implant.
In addition, U.S. Pat. No. 5,020,519 to Hayes et al. discloses an instrument for seating a spine rod into a hook. The instrument grips the hook with teeth and clamps the hook between the jaws. The thumb wheel must be rotated to shift the pusher thereby urging the spine rod into the hook. Again, it is difficult to utilize this instrument with a single hand.
There remains a need for improved instruments for urging or persuading spinal rods into position in orthopedic devices such as coupling elements or implants. In particular, there remains a need for spinal rod persuaders that may be effectively utilized with one hand. Moreover, there is a need for a simple design that both holds the coupling element stationary while persuading the rod into position. There is a further need for a rod persuader that locks as the rod is advanced into position. It is advantageous for a rod persuader to be easily removed from gripping the coupling element after the rod is properly positioned. It is further advantageous to provide a cannula in the rod persuader in which a set screw or other fastener may be inserted and delivered to the coupling element while the rod persuader is gripping the coupling element and rod.
According to one aspect of the invention, a rod persuader or an apparatus for urging an orthopedic or spinal rod into a recess or seat on an orthopedic device such as an implant, coupling element, or pedicle screw system is provided. The apparatus includes a body that is releasably attachable to the orthopedic device, pusher member and a trigger slidingly coupling the pusher member to the body.
The trigger may be actuated to translate the pusher member into contact with the rod and continue translating the pusher member until the rod is urged into recess of the orthopedic device. The pusher bar comprises a slide coupled to the body via the trigger and a sleeve attached to the slide so that the slide and sleeve translate together. Additionally, the sleeve includes at least one pusher bar integral with the sleeve and for accommodating the rod upon contact. Furthermore, the rod persuader may include a grip extending from the body and a handle extending from the trigger so that the rod persuader may be comfortably held in one hand. The handle is movable toward the grip to actuate the trigger.
According to another aspect of the invention, the rod persuader has a pair of fingers extending from an end of the body. The fingers are adaptable to releasably grip the orthopedic device. The fingers are elastic members that are separable to receive and grip the orthopedic device therebetween. The fingers may further include projections that cooperate with recess on the orthopedic device that allows the rod persuader to snap onto the orthopedic device. Additionally, the sleeve may include portions such as arms that prevent the fingers of the body from separating while gripping the orthopedic device as the sleeve is advanced.
According to another aspect of the invention, the rod persuader defines a cannula for receiving a fastener and a driver to secure the rod to the orthopedic device. The body and/or the pusher member may have channels which together form the cannula.
According to another aspect of the invention, a rod persuader or apparatus for urging and securing an orthopedic rod to an orthopedic device is provided. The apparatus includes a body releasably attachable to the orthopedic device, a pusher member coupled to the body via a trigger, and a ratchet. Actuation of the trigger translates the pusher member into contact with the rod and urges the rod into the recess of the orthopedic device, the ratchet controls the translation of the pusher member in steps so that after each step, the ratchet locks into position to prevent the pusher member from reverting backwards.
The pusher member comprises a slide slidingly coupled to the body, a sleeve attached to the slide, and at least one pusher bar integral with the slide. A grip may extend from the body and a handle may extend from the trigger. An elastic member is operatively associated with the grip and handle to hold the handle in a normally open position so that moving the handle toward the grip actuates the trigger to advance the ratchet. Thus, the elastic member locks the ratchet in position at each step. According to another aspect of the invention, the ratchet is attached to the handle or the grip. The ratchet comprises a rack having a plurality of female teeth. Each of the teeth on the rack corresponds to one step of the ratchet. The rack further includes a hinge connecting the rack to the grip or the handle and a male tooth extending opposite the female teeth from the handle or the grip and cooperating with the female teeth. Thus, as the handle is moved toward the grip, the male tooth is advanced to the first female tooth and locked into position. The male tooth advances along the rack of the female teeth each time the handle is moved and the male tooth locks in at each step. As this occurs, the pusher member translates in steps to urge the rod into position. The ratchet is unlocked by rotating the rack about the hinge.
According to yet another aspect of the invention, the ratchet comprises a plurality of female teeth defined in the pusher member or the body and a male tooth extending opposite the female teeth from the body or the pusher member. Moving the handle, thus actuates the trigger to translate the pusher member and advance the male tooth along the female teeth, step-by-step, locking in at each step. A tab extends from the body and is operable to unlock the ratchet. In one aspect of the invention, the pusher member includes a slide coupled to the body via the trigger, a sleeve attached to the slide, and at least one pusher bar for direct contact with the rod.
In accordance with another aspect of the invention, the body may further include a pair of fingers for releasably gripping the orthopedic device. The sleeve includes portions such as a pair of arms for preventing the fingers of the body from separating while holding the orthopedic device when the sleeve is translated. The rod persuader also includes a cannula formed by the channels of the slide and body. The pusher bar further defines a recess for accommodating the rod.
According to yet another aspect of the invention, an apparatus for securing a spinal rod to a pedicle screw is provided. The apparatus includes a generally longitudinally body defining a channel, a generally longitudinal pusher member defining a channel, a cannula formed by the channels, a ratchet, a grip extending from the body, a trigger slidingly coupling the pusher member to the body, a handle extending from the trigger, and a handle extending from the body. The handle is movable toward the grip to actuate the trigger and thereby translate the pusher member toward the spinal rod and into contact therewith. The ratchet controls the translation of the pusher member and rod in steps, locking at each step. An elastic member is associated with the grip and handle to return the handle back to a normally open position after it has been moved.
The apparatus may further include a pair of elastic fingers extending from the body that are separable to receive and grip the pedicle screw. The pusher member may include a slide attached to the body via the trigger, a sleeve and at least one pusher bar. The sleeve may include a pair of arms extending therefrom for preventing the fingers from separating.
According to another aspect of the invention, the ratchet includes a plurality of female teeth and a male tooth. The female teeth may be defined on a rack attached to the handle or grip via a hinge, or the female teeth may be defined in the slide or the body. Accordingly, the male tooth extends opposite the female teeth at the grip or handle, or the male tooth is defined opposite the female teeth in the body or slide.
According to yet another aspect of the invention, a method for securing an orthopedic rod to an orthopedic device using a rod persuader including a body having a grip extending therefrom, a pusher member and a trigger coupling the pusher member to the body and having a handle extending therefrom is provided. The method includes the steps of holding the rod persuader in a single hand, engaging the orthopedic device via a pair of fingers extending from the body, displacing the handle toward the grip to actuate the trigger and thereby advance the pusher member, contacting the rod with the pusher member, displacing the handle further to advance the rod into the seat of the orthopedic device, securing the rod to the orthopedic device and releasing the rod persuader from the orthopedic device.
In accordance with another aspect of the invention, the engagement of the orthopedic device further includes contacting the fingers of the body with the orthopedic device and applying a force to the body to separate the fingers allowing for insertion of the orthopedic device between the fingers. The securing step further includes inserting a fastener into the cannula and using a driver to tighten the fastener to secure the rod to the orthopedic device.
According to another aspect, the method further includes removing the driver and removing the apparatus from the orthopedic device by applying a force to the body away from the orthopedic device.
In accordance with another aspect of the invention, a method for securing a rod to an orthopedic device is provided. The method utilizes a rod persuader including a body with a grip, a pusher member, a trigger with a handle, a ratchet, and an elastic member connecting the handle to the grip. The method includes holding the rod persuader in a single hand, engaging the orthopedic device via fingers on the body, displacing the handle to actuate the trigger and advance the ratchet one step, and thereby translate the pusher member, locking the ratchet in position at the step, and repeatedly displacing the handle to advance the rod into position step by step.
The engaging step may include contacting the fingers with the orthopedic device and applying a force to the body to separate the fingers to allow for insertion of the orthopedic device there between.
According to another aspect, the securing step includes inserting a fastener into the cannula and using a driver to tighten the fastener to secure the rod to an orthopedic device. Finally, the rod persuader is released from the orthopedic device by unlocking the ratchet and applying a force to the body away from the orthopedic device to separate the fingers thereby releasing the rod persuader.
The method may further include inserting a fastener into the cannula and using a driver to tighten the fastener to secure the rod to the orthopedic device.